update some book figures

Review URL: https://chromiumcodereview.appspot.com/12632019
move dart-web-components to web-ui; remove duplicate dart2js and dart-vm pages

Also general link cleanup. Staged at:

http://webui.dart-lang.appspot.com/

BUG=8105

Review URL: https://chromiumcodereview.appspot.com/12615008
fix feedback link

BUG=

Review URL: https://chromiumcodereview.appspot.com//12929007
add style for cascades

BUG=

Review URL: https://chromiumcodereview.appspot.com//12730022
Basic necessities for article tests.

Review URL: https://chromiumcodereview.appspot.com/12717012
Adding io doc code test
Adding json test code
Adding js code
Added runtests.bat to enable fairly rudimentary support for running article tests on windows
Merge pull request #41 from chrisbu/windows_test_script

Added runtests.bat for windows support
Added Streams article from dartwatch
Fix missing imports and updated article
Adding pub spec and organizing code blocks
Merge pull request #40 from financeCoding/io_article_code

Adding io doc code test
Added a file with all of the code from the future article.
Including pubspec and cleaned up article
Merge pull request #44 from dart-lang/futures_and_errors_handling_tests

Added a file with all of the code from the future article.
Merge pull request #43 from financeCoding/js_article_code

Js article code
Adding test code and updating article
Run pub if there's a pubspec.yaml in the code/ subdir when running article tests.